JP2580812B2 - Polyurethane / polyamide-based composite fiber and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a self-crimping conjugate fiber comprising a polyurethane and a polyamide. More specifically, the present invention relates to a polyurethane / polyamide-based composite fiber having excellent recovery stress characteristics and heat resistance, and particularly useful as a stocking or tricot material having excellent fit and transparency.

[Prior art] Self-crimping conjugate fibers obtained by eccentrically compounding polyurethane and polycapramid can be used as a knitted fabric having excellent crimping properties and transparency, and are therefore highly used as materials for high-grade stockings. Has been evaluated.

Examples of the polyurethane component in the composite fiber include a polyol, a polyether composed of a polyalkylene oxide, polytetrahydrofuran, or the like; a polylactone obtained by, for example, polymerization of ε-caprolactone; an acid such as adipic acid or glutaric acid; Polyesters obtained by condensation polymerization from glycols such as glycols; or polycarbonates, obtained by reacting these polyols with diisocyanates and conducting chain extension with low molecular weight diols or hydrazine or ethylenediamines. Known elastic polyurethanes are known.

Among these polyurethane compounds, it is possible to copolymerize or mix a polycarbonate-based polyurethane having excellent peel resistance with the polyamide component and relatively excellent heat resistance with another polyester-based polyurethane or polyether-based polyurethane. It is considered to be good.
No. 570, Japanese Patent Publication No. 57-34370).

[Problems to be Solved by the Invention] Even if an eccentric conjugate fiber is produced using the above-mentioned conventional polyurethane component, a considerably excellent coiled crimp can be obtained. There has been a demand for polyurethane / polyamide eccentric conjugate fibers that are strong and have higher fitting properties.

Further, in the conventional polyurethane / polyamide conjugate fiber, since the heat resistance of polyurethane is inferior to that of polyamide, there is also a problem that the heat treatment in the post-processing step deteriorates the fitting property or the durability of the product.

Therefore, the present invention improves the recovery stress characteristics after the onset of crimp without impairing the excellent elongation and recovery characteristics of the polyurethane elastic body, further improves the heat resistance, and improves the characteristics of the product after heat treatment. It is a main object of the present invention to provide a polyurethane / polyamide-based composite fiber that can be used.

[Means for Solving the Problems] To achieve the above object, an eccentric polyurethane / polyamide fiber according to the present invention is an eccentric conjugate fiber comprising a polyurethane component and a polyamide component, wherein the polyurethane component has a DSC melting peak. It is characterized by comprising an elastic polyurethane having a temperature of 190 to 230 ° C.

The elastic polyurethane used as the polyurethane component in the present invention needs to have a DSC melting peak temperature of 190 to 230 ° C. The temperature is preferably 192 ° C. or higher,
It is preferable that the temperature is not lower than ° C. This peak temperature is 190 ° C
If it is less than 1, heat resistance and elongation recovery characteristics are inferior, so that the object of the present invention cannot be achieved. The peak temperature is at most about 230 ° C., and preferably about 220 ° C. If this peak temperature exceeds 230 ° C., it is difficult to obtain a sufficiently excellent product because the feeling (soft feeling) and the elongation recovery characteristics of the stretch knitted fabric product such as stockings are inferior.

 This peak temperature may be obtained by the following method.

Approximately 10 mg of a sample is packed in an aluminum pan, and a DSC melting curve is determined using a differential scanning calorimeter (DSC): “DSC-4” manufactured by Perkin Elmer, Inc. at a temperature rising rate of 10 ° C./min and a sample of approximately 10 mg. The melting curve has one or more endothermic peaks. Among the endothermic peaks, a peak substantially at the highest temperature relating to the melting of the hard segment crystal part is taken, and the peak temperature is defined as a DSC melting peak temperature.

For example, in the figures showing the DSC melting curves for Nos.A1, B2 and C2 in the examples, when a single peak is shown as the melting curve of A1, the temperature of that peak is shown as the melting curve of C2. When there are several peaks, the temperature of the peak on the hottest side is read, and when the decomposition exothermic peak interrupts the melting peak as in the melting curve of B2, the corrected peak is repeatedly read, and What is necessary is just to take the temperature of the peak on the high temperature side.

In the DSC measurement, a polyurethane component is obtained by completely dissolving and removing only the polyamide component from the conjugate fiber with formic acid at room temperature, and after washing with water, air-drying for 12 hours or more, this polyurethane component may be used as a sample for measurement.

The DSC melting peak temperature of this elastic polyurethane is 190 to 23.
In order to set the temperature range to 0 ° C., a means for adjusting the ratio of the crystal forming portion (hard segment) of polyurethane, the polyurethane melting temperature, the molecular weight of the polyol component, the blocking property of the low molecular weight diol portion, or the like is used. In order to adjust the orientation characteristics and crystal structure perfection of the conjugate fiber, a combination of aging, elongation and heat treatment may be used.

For example, when adjusting the ratio of the hard segment (chain extender such as low molecular diol and diamine) and the soft segment (polyol component) of polyurethane, the weight ratio of low molecular diol / polyol is adjusted to 17:83 to 25. : 75 range. Further, the range of 20:80 to 25:75 is preferable. Further, in order to make the DSC melting peak temperature 190 to 230 ° C., it is preferable to perform a heat treatment at a temperature of about 70 to 160 ° C. subsequent to the drawing, and this heat treatment further increases the heat resistance in the high-order processing of the conjugate fiber. Can be improved.

In order to obtain the composite fiber specified in claim 1, it is preferable to use an elastic polyurethane having a 100% tensile stress of 150 kgf / cm ² or more at the stage of the polyurethane component before melt spinning. The conjugate fiber obtained by using this elastic polyurethane has further improved heat resistance, fitability, feeling, elongation recovery characteristics, and crimp characteristics of the obtained stretch knitted fabric product.

The value of the 100% tensile stress is a value measured by the JIS K7311 method, and may be measured at a tensile speed of 300 m / min using a 2 mm thick sheet by injection molding.

As the kind of the elastic polyurethane, an elastic polyurethane such as a polycarbonate-based polyurethane, a polyester-based polyurethane, a polylactone-based polyurethane, and a polyether-based polyurethane may be used alone, in a copolymer, or in a mixture. Among them, an elastic polyurethane consisting essentially of a polycarbonate-based polyurethane or an elastic polyurethane containing 10% by weight or more of a polycarbonate-based polyurethane as a copolymer component or a mixed component is preferred from the viewpoint of adhesiveness to a polyamide component and the like. . In addition, a small amount that does not impair properties such as peel resistance with polyamide, thermoplasticity, thermal stability, strong elongation and elasticity (for example, 20
(% By weight, preferably 10% by weight or less), other compounds such as polyester and polyisocyanate may be mixed.

Polyols for obtaining the polycarbonate-based polyurethane include 4,4'-dioxydiphenyl-2,2 '
-An aromatic polycarbonate from propane (bisphenol A), and an aliphatic polycarbonate obtained by reacting an aliphatic dihydric alcohol with phosgene. Examples of the polyol for obtaining the polyether-based polyurethane include poly (oxyethylene) glycol, poly (oxypropylene) glycol, and poly (tetramethylene) glycol. Furthermore, polyols for obtaining polyester-based polyurethanes include acids such as adipic acid, glutaric acid or sebacic acid, ethylene glycol, 1,4-butylene glycol, 1,3- or 2,3-butanediol, 2 And polyesters obtained by a condensation reaction with glycols such as 1,5-hexanediol. The molecular weight of these polyols is preferably about 600 to 4000.

Further, as a diisocyanate for obtaining an elastic polyurethane, diphenylmethane diisocyanate, tolylene diisocyanate, naphthalene diisocyanate,
Examples include isophorone diisocyanate and lysine diisocyanate. Examples of the chain extender include low molecular weight glycol, hydrazine, ethylenediamine, bis-β-hexanone and the like. The molar ratio (-NCO / -OH) between the -NCO terminal group and the -OH terminal group in the polymerization raw material may be about 1.00 to 1.15.

These polymerization raw materials can be polymerized by an ordinary polyurethane polymerization method such as a one-shot method or a prepolymer method, or further mixed with a polymer or an additive to obtain an elastic polyurethane used as a base polymer of a polyurethane component.

In order to suppress the variation in viscosity during melt spinning of the elastic polyurethane, it is effective to control the degree of polymerization of the polyurethane to an appropriate range according to the polyurethane composition, and generally, the melt viscosity is about 3500 to 35,000 poise. Is preferred.

On the other hand, the polyamide component used in the present invention may be a melt-spinnable polyamide such as nylon 6, nylon 66, nylon 6,10, or a copolymerized polyamide thereof. In order to obtain a composite fiber with good physical properties such as abrasion,
It is preferable to use a polyamide having a melting point of 200 ° C. or higher. However, a polyamide having an excessively high melting point is not preferable for complex spinning with polyurethane, and it is practically preferable that the melting point is at most about 300 ° C. Among them, a polyamide having a melting point of 210 ° C. or more is preferable,
In particular, a polyamide substantially consisting of nylon 6 or nylon 66 is preferred. The degree of polymerization only needs to have a relative viscosity ηr of a degree used for clothing fibers, and for example, a sulfuric acid relative viscosity of about 2.0 to 2.8. The polyamide component may contain usual additives such as a heat-resistant agent, a light-resistant agent, and a matting agent.

The above-mentioned polyurethane component and polyamide component may be basically spun in the same manner as a conventional melt composite spinning of polyamide and polyurethane to form eccentric composite fibers. For example, a normal spinning method in which each polymer (composition) is supplied to a normal melt compound spinning machine and melted separately, and then compound spinning and stretching using a compound spinneret heated to about 230 to 290 ° C. What is necessary is just to manufacture a latent crimpable conjugate fiber by the method. The stretching method may be hot stretching or cold stretching, and cold stretching is particularly preferable from the viewpoint of uniformity. Further, relaxation heat fixing may be performed.

The composite structure may be any eccentric composite structure that provides a potential crimp that can exhibit a coiled crimp by crimp development processing, and examples thereof include an eccentric core-sheath composite structure and a side-by-side bonded composite structure. Can be The composite ratio also depends on the composite structure, but is generally 80/20 to 2
It may be about 0/80. Further, it is preferable that the polymer occupying the outer peripheral surface of the fiber is a polyamide or that the ratio thereof is large.

Polyurethane obtained by melt composite spinning
The polyamide eccentric conjugate fiber is crimped by a usual method and exhibits elastic properties as a coiled crimped fiber.

[Action] In the conjugate fiber according to the present invention, the elastic polyurethane constituting the polyurethane component has a higher DSC of 190 ° C. or higher than the conventional one.
Since it has a melting peak temperature, the heat resistance of the conjugate fiber is excellent, and further, excellent strength and elongation / recovery properties can be exhibited.

Therefore, when this composite fiber is used, knitting, weaving, dyeing, heat setting, and performing post-processing such as crimping as a final product, the reduction in physical properties at the time of subsequent processing is greatly improved. The strength and elongation characteristics of the fibers are greatly improved compared to conventional knitted fabrics made of polyurethane / polyamide fibers.
It can exhibit excellent strength and elongation recovery characteristics, is practical, has a high fit, and has a fine crimp, a beautiful stitch, and an excellent texture.

On the other hand, in the conventional conjugate fiber, the DSC melting peak temperature of the elastic polyurethane constituting the polyurethane component is 190.
Since the temperature is lower than 0 ° C., the heat resistance and the elongation recovery characteristics cannot be said to be sufficient, and there are great restrictions on heating in the post-processing step in the practical production of stockings.

The DSC melting peak temperature is an indicator of heat resistance and is related to the stress during elongation recovery. That is, the higher DSC melting peak temperature means that the crystal perfection of the crystal part (hard segment), which is a nodule part of the elastic polyurethane, is increased, and further, the number of crystal domains is increased. It has rubber elasticity. Therefore, in order to improve the elongation recovery stress and the heat resistance that contribute to the fit of the woven product, the DSC melting peak temperature must be 1
It is effective to set the temperature to 90 ° C. or higher, which is higher than the conventional level.

[Examples]-Example 1 A 1: 1 mixed polyol of a polycarbonate ester and a polycaprolactone having a number average molecular weight of 2,000 respectively was used, 1,4-butylene glycol was used as a chain extender, and diphenylmethane diisocyanate was used as a diisocyanate. And a polyurethane polymer was obtained by polymerization using an ordinary one-shot method. After the obtained polymer was pulverized, it was melt-extruded with an extruder and pelletized.

In the above polymerization, -NCO terminal group and -O
The molar ratio with the H terminal group (-NCO / -OH) was set to 1.07. Also, two kinds of elastic polyurethanes having different weight ratios of 1,4-butylene glycol / mixed polyol as 16/84 or 21/79 were synthesized. Adjust the polyurethane viscosity level during synthesis, and the melt viscosity is 10,000 poise or 20,000 poise respectively.
Elastic polyurethane.

The melt viscosity and 100% tensile stress of each of the obtained elastic polyurethanes were measured, and the results are shown in Table 1.

These elastic polyurethanes and 98% sulfuric acid polycapamide having a relative viscosity of 2.40 were separately melted at 230 ° C and 260 ° C, respectively, and supplied to a composite spinning machine. Spinning out composite to core-sheath shape,
Cooled, lubricated and wound at 600 m / min by the usual method After stretching the obtained undrawn yarn about 4.0 times, it continuously runs on a hot plate set at normal temperature to 140 ° C in a constant length state Let
A heat-treated 20 denier, 2 filament latently crimped composite filament yarn was obtained. The obtained filament yarn was measured for the elongation characteristics and the DSC melting temperature of the polyurethane component. The results are shown in Table 1. The melting curves of the polyurethane components in Nos. A1, B2 and C2 are shown in the figure.

The composite filament yarn is knitted into a stocking knitted fabric at a knitting speed of 800 rpm using a usual method, and heat-set with 110 ° C. steam to produce a stocking product.
The elongation-recovery stress characteristics, fitability and feeling were measured, and the results are shown in Table 1.

 The measurement of the above physical properties was performed by the following methods.

Stocking crimp characteristics: constant elongation type tensile tester TOM-1
Using a 00E type (manufactured by Shinko Tsushin Kogyo Co., Ltd.), the length of the stocking sample when it was stretched by applying a load of 2 kg was L1, and this stocking sample was folded in two and placed on a tensile tester. The hysteresis curve of the stress strain which was stretched to 75% of the strain and immediately recovered was drawn. From this hysteresis curve, the stress value (g) at the time of elongating 75% of L1 / 2
And the stress value (g) at the time of recovery to the length of 60% elongation of L1 / 2 from the curve at the time of recovery.
The values obtained in Table 1 were expressed as 75% elongation stress and 60% recovery stress, respectively. These values are indices indicating the fit of the stocking, and the higher the value, the better the fit.

Fit and hand: Relative evaluation results obtained by wearing test of product stockings, ◎: extremely good, ：: good, Δ: slightly poor, ×: poor.

As is clear from the results in Table 1, in the case of the conjugate fiber composed of an elastic polyurethane having a polyurethane component having a DSC melting peak temperature of 190 ° C. or more, the strength and elongation characteristics, the fit of stockings, and the feeling were excellent. . When elastic polyurethane (No. C and D) having 100% tensile stress of 150 kgf / cm ² or more is used as the polyurethane component,
These properties were further excellent, resulting in a very good product.

[Effect of the Invention] Since the polyurethane / polyamide eccentric conjugate fiber according to the present invention is constituted by an elastic polyurethane having a DSC peak temperature of 190 ° C or higher, the recovery stress characteristic of the coiled crimped fiber after the onset of crimping is improved. The knitted fabric product can be remarkably improved, and the fit property can be further improved.

In addition, since the heat resistance is improved, it is possible to prevent quality deterioration during crimping treatment or heat setting, and it is also possible to improve the strength and elongation characteristics of the stretchable knitted fabric product.

The conjugate fiber according to the present invention can be widely used for textile products requiring high fitting properties, but is particularly useful for stockings and stretchable tricot products, and is also used for other hogaries such as socks. Can be.

[Brief description of the drawings]

The figure illustrates DSC melting curves of the polyurethane component, of which B2 and C2 illustrate the melting curves of the polyurethane component of the conjugate fiber according to the present invention.

Claims (3)

(57) [Claims] 1. An eccentric conjugate fiber comprising a polyurethane component and a polyamide component, wherein the polyurethane component comprises an elastic polyurethane having a DSC melting peak temperature of 190 to 230 ° C. . 2. The method according to claim 1, wherein at least 10% by weight of the elastic polyurethane is
The polyurethane / polyamide composite fiber according to claim 1, wherein the polyurethane / polyamide composite fiber is a polycarbonate polyurethane. 3. A polyurethane / polyamide composite fiber according to claim 1, wherein said polyurethane component and said polyamide component are melt-spun and stretched to produce a polyurethane / polyamide-based composite fiber. Is an elastic polyurethane having a tensile stress of 17:83 to 25:75 and a 100% tensile stress of 150 kgf / cm ² or more, and a heat treatment at 70 to 160 ° C. following stretching. A method for producing polyurethane / polyamide composite fibers.